Recently, wireless data, entertainment and mobile communications technologies have become increasingly prevalent, particularly in the household environment. The convergence of these wireless data, entertainment and mobile communications within the home and elsewhere has created the need for merging many disparate devices into a single wireless network architecture capable of seamlessly supporting and integrating the requirements of all of these devices. Seamless connectivity and rapid transfer of data, without confusing cables and wires for various interfaces that will not and cannot talk to each other, is a compelling proposition for a broad market.
To that end, communication industry consortia such as the MultiBand Orthogonal Frequency Division Multiplexing (OFDM) Alliance (MBOA), the Digital Living Network Alliance (DLNA), the WiMedia Alliance and the like, are establishing design guidelines and standards to ensure interoperability of these wireless devices. For example, Wireless 1394, Wireless USB, and native IP-based applications are currently under development based on ultrawideband (UWB) radio or WiMedia Convergence Platform.
Although it began as a military application dating from the 1960s, UWB has recently been utilized as a high data rate (480+Mbps), short-range (up to 20 meters) technology that is well suited to emerging applications in the consumer electronics, personal computing and mobile markets. When compared to other existing and nascent technologies capable wireless connectivity, the performance benefits of UWB are compelling. For example, transferring a 1 Gbyte file full of vacation pictures from a digital camera to a computer take merely seconds with UWB compared to hours using other currently available, technologies (i.e. Bluetooth) and consume far less battery power in doing so.
UWB has also generated some concerns, however. In particular since UWB signals are spread over a broad swath of spectrum there has been concern that UWB will degrade the performance of other users of the spectrum encompassed by the UWB radio. Typically, devices which employ UWB utilize a fixed channel bandwidth that is static in frequency, or a fixed channel bandwidth that can be frequency agile. In either case, the bandwidth utilized by a device may remain substantially fixed. Thus, the range and data rate of the device is, for the most part, determined by the modulation/coding of the signal, and the power with which the signal is transmitted.
In most cases as UWB, by definition, is spread over a broad spectral range, the power spectral density of a signal utilized by a UWB device is usually very low, and hence, usually results in low incidence of interference with other systems which may be utilizing the same bandwidth as the UWB device or system. Power spectral density, however, is a function of distance. Consequently, if a UWB device was in close proximity to another wireless system there may be the potential for interference between the UWB device and the wireless system.
Consequently, there may be one or more frequency ranges within a UWB frequency spectrum where it is important to suppress interference. It may be desired to suppress interference within these frequency ranges for a variety of reasons. One of these reasons is the existence of existence of other devices which utilize at least a portion of the frequency ranges. As noted above, UWB encompasses a broad frequency range, thus the opportunity for interference between UWB devices and the myriad number of other device which either currently use portions of the UWB frequency spectrum or which are being designed to utilize a portion of this frequency spectrum (e.g. Broadband Fixed Wireless Access Systems such as IEEE 802.16e or WiMax, Bluetooth systems, etc.) may exist.
Additionally, certain regulatory environments may dictate that a device not emit within certain frequency ranges (or that emissions in the frequency ranges are below a certain level). For example, some existing UWB spectrum allocations encompasses the frequency range utilized by the C-Band satellite downlinks. Thus, there is a potential for UWB systems to interfere with the reception of those types of system and certain regulatory entities or governing bodies have dictated that devices may not emit in the spectrum allocated for C-Band satellite.
As can be seen then, being able to control the transmission properties of a UWB (or other type of radio) signal is important for a myriad number of reasons, including regulatory decrees, commercial feasibility and interference issues. One approach to deal with these types of issues is to apply a spectral mask to a UWB signal prior to its transmission. Utilizing a spectral mask interference or overlap between the frequencies of a transmitted UWB signal and the frequencies utilized by other systems may be minimized.
While this approach may be useful for certain regulatory environments it is an overly draconian approach as it requires a UWB device to avoid emissions in a given frequency range, even if the frequency range is not currently in use by any other device within the range of the UWB device. Consequently, the performance of the UWB device may be degraded for no reason. Furthermore, if other systems or devices begin to emit in the frequency spectrum which is being utilized by the UWB device, the UWB device does not have the ability to detect and mitigate this interference, as the frequency range in which the UWB radio suppresses emissions is substantially fixed by the spectral mask.
Thus, there is a need for systems, apparatuses and methods for radios which are capable of determining potential interference within a frequency spectrum and dynamically adjusting the transmission properties of the radio accordingly.